[Python-de] Sorting string lists and merging lists

[Mike Müller]

Am 13.05.13 12:35, schrieb c.schmitt at briefdomain.de:
> Hi, I have 2 Lists like this:
> list1 = ["ML2", "ML4", "ML6", "ML8", "ML10", "ML12"]
> list2 = ["ML4", "ML6", "ML8", "ML10", "ML12", "ML14", "ML16", "ML18", "ML20"]
> 
> Now i want to merge these list and sort out double elements. At the moment i can do this, but i don't think it's that efficient:
> 
>         new_list = list1
> 
>         for element in list2:
>             if element not in list1:
>                 new_list.append(element)
> 
> And after that I want to sort the lists that it is sorted after the number like:
> ML2, ML4, ML6, etc.. (ML is always ML and won't be changed)
> 
> Is there a way to do this?

Sets and sorting with `key` should solve your problem:

list1 = ["ML2", "ML4", "ML6", "ML8", "ML10", "ML12"]
list2 = ["ML4", "ML6", "ML8", "ML10", "ML12", "ML14", "ML16", "ML18", "ML20"]
merged = set(list1).union(set(list2))
sorted_by_number = sorted(merged, key=lambda x: int(x[2:]))
print sorted_by_number

Output:
['ML2', 'ML4', 'ML6', 'ML8', 'ML10', 'ML12', 'ML14', 'ML16', 'ML18', 'ML20']


HTH,
Mike

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